1. Field of the Invention
This invention relates to a method of controlling the operation of an Automated Guided Vehicle (hereinafter abbreviated to A.G.V.) used as a means of transportation for production line work performed in a machine manufacturing works.
2. Description of Prior Art
In general, production line work in a machine manufacturing works, such as an automobile manufacturing works, is usually performed with a conveyor system. In particular, with respect to production line work, mainly consisting of manual operations, the relevant operations are usually performed by using a conveyor system. This is because a well-paced performance, based on the continuous flow of a conveyor, is regarded as important.
However, a production line used with a conventional an ordinarily conveyor system ordinarily involves a number of work stages, and the length of the production line is inevitably quite considerable. The size of the installation is thus correspondingly increased; and it is difficult to provide paths for the movement of workers and the supply of parts. Such a conveyor system is also defective in terms of adaptability to changes in the overall layout of the works.
The introduction of A.G.V.'s to parts assembly lines, or parts packaging lines, is currently being eagerly studied as an alternative to the use of conveyor systems. Examples of an technique allowing such applications are disclosed in Japanese Patent Laid-Open No. 60-137476, "AUTOMATION" (published by Nikkan Kogyo Shinbun Shia in 1986, Vol. 31, No. 8, pp 36-42), and "MATERIAL HANDLING ENGINEERING" (published by PENTON-IPC in USA,1985, pp 52-56).
In all the techniques for introduction of A.G.V.'s disclosed in these documents, the speed at which an A.G.V. travels is constant, and an operation of assembling or packaging parts is performed each time the vehicle stops at a station for a predetermined period of time. Consequently, such a vehicle system cannot serve as a way of maintaining a desired pace, and cannot constantly maintain a certain level of working hours and production line speed, thus resulting in a lowering of production efficiency.
In the system disclosed in Japanese Patent Laid-Open No. 60-137476, the stopping time at each station is controlled in accordance with the time taken by each work stage in a production line. In this system, lamps may be provided at each station in order to inform workers of the passage of working time or the time remaining for the given task. However, this system cannot serve to maintain a certain pace commensurate with the performance of production line work since the pace keeping function of this system does not become second nature to a person, like the continuous flow of a conveyor system. There is a possibility that, it will result in non-uniform tasks. There is also a problem in that the administrator or supervisor cannot ascertain the progress of operation as being either ahead of, or behind time, relative to a standard.